Humidifier tub for CPAP device

ABSTRACT

A humidifier tub includes a first side having an air inlet opening configured to receive the pressurized flow of respiratory gas. A second side opposes the first side. An air outlet opening is configured to discharge the pressurized flow of respiratory gas with added humidity. An inlet passage extends from the air inlet opening toward the second side so that the pressurized flow of respiratory gas travels through the inlet passage in a first direction. A guidance structure is located between the first and second sides and positioned so that a traveling direction of the pressurized flow of respiratory gas changes from the first direction to a second direction upon the pressurized flow of respiratory gas engaging the guidance structure. The guidance structure extends downward from a lid. In addition, the first direction is a lateral direction and the second direction is a downward direction.

CROSS-REFERENCE TO PRIORITY APPLICATION

This application is a continuation of U.S. application Ser. No.16/855,180, filed Apr. 22, 2020, now allowed, which is a continuation ofU.S. application Ser. No. 15/332,037, now U.S. Pat. No. 10,661,043,filed Oct. 24, 2016, which is a continuation of U.S. application Ser.No. 11/988,718, now U.S. Pat. No. 9,707,370, filed Jan. 14, 2008, whichis the U.S. national phase of International Application No.PCT/AU2006/001171 filed 15 Aug. 2006 which designated the U.S. andclaims priority to U.S. Provisional Application No. 60/707,949 filed 15Aug. 2005, the entire contents of each of which are hereby incorporatedby reference.

FIELD OF THE INVENTION

The present invention relates to an improved humidifier tub that isadapted to form part of a Continuous Positive Airway Pressure (CPAP)flow generator with a humidification system used to treat sleepdisordered breathing (SDB) conditions such as Obstructive Sleep Apnea(OSA).

BACKGROUND OF THE INVENTION

Colin Sullivan was the first to invent the use of nasal ContinuousPositive Airway Pressure (CPAP) to treat Obstructive Sleep Apnea (OSA),e.g., see U.S. Pat. No. 4,944,310. The treatment generally provides asupply of air or breathable gas from a blower to a patient via an airdelivery conduit and a patient interface, such as a full-face or nasalmask or nasal prongs. The air or breathable gas is commonly delivered ata pressure of 4cmH₂O to 20cmH₂O and acts as a splint to hold the airwayopen during sleep.

Humidifiers are commonly used with CPAP flow generators to prevent apatient's airways from drying out. The humidified air is generallyheated allowing the air to carry more moisture and to provide additionalcomfort for the patient. A humidifier normally comprises a water tub, aheating element, an air inlet able to receive air from the CPAP flowgenerator, and an outlet adapted to connect to a delivery conduit todeliver the humidified air through the patient interface to the patient.A humidifier may be integrated or adapted for coupling with a CPAP flowgenerator. The humidifier is often detachable to allow the water tub tobe removed for filling with water.

Humidifier tubs may be washable or disposable. Disposable humidifiertubs are well known in the prior art, e.g., see U.S. Pat. No. 4,203,027(O'Hare et al.) published 13 May 1980 and U.S. Pat. No. 6,398,197(Dickinson et al.) published 4 Jun. 2002.

As humidifier systems and tubs become smaller, the surface area of waterexposed to the delivered air also inherently becomes smaller, creatingproblems in maintaining a sufficient moisture pickup by the air flowpassing through the tub. The use of baffles between the air inlet andair outlet has been used to encourage the incoming air to flow aroundthe surface of the container and down to the water surface prior toexiting from the air outlet. This suffers from the disadvantage that theair flow suffers a significant pressure drop, thus requiring the flowgenerator motor to run faster to overcome this drop in pressure andconsequently producing more noise.

Another problem with current humidifier tubs is that if the tub isfilled above the indicated level, in particular while the tub isconnected to the flow generator, the water may flow back into the flowgenerator.

A further problem with prior art humidifier tubs, especially round tubs,was that users, particularly those users with limited dexterity or pooreyesight or under low light conditions, may have difficulty in correctlyorienting the tub for attachment onto the cradle.

SUMMARY OF THE INVENTION

One aspect of the invention relates to a low cost humidifier tub thatallows increased moisture pickup by the air flow while minimizingpressure loss when the air travels through the tub.

Another aspect of the invention relates to a humidifier tub thatdecreases or prevents the chances of water flowing back into the flowgenerator if the tub is overfilled. In one example, a humidifierincludes a humidifier tub including an air inlet and an air outlet. Theair outlet has an exit port having a lower-most portion that ispositioned in a plane disposed below a lower-most portion of the airinlet. Further, the outlet of the humidifier is preferably lower thanthe outlet of the flow generator. Thus, over-filling will result inwater emerging from the outlet rather than through the inlet andpossibly into the flow generator. In addition or in the alternative, theinlet may be in the form of an inlet tube that is angled relative tohorizontal such that water is guided from the inlet tube towards thewater chamber.

Another aspect of the invention relates to a humidifier tub thatprovides a user guidance structure/system used during attachment of thetub to the heating cradle. The guidance structure may include generallyflat converging side walls that provide guidance when inserting the tubinto the humidifier unit/cradle.

Another aspect of the invention relates to a humidifier tub that is easyto manufacture (e.g., via molding) and/or requires simplified tooling.

Another aspect of the invention relates to a humidifier tub that iscompact in size yet delivers appropriate moisture content to the flow ofair.

Another aspect relates to a humidifier tub having a shape that reducespressure loss.

Another aspect of the invention relates to a humidifier including ahumidifier tub including an air inlet and an air outlet. The air outlethas an exit port positioned in a plane disposed below the air inlet. Abase plate is provided to a bottom of the humidifier tub. The base plateand humidifier tub define a water chamber adapted to receive a volume ofwater. The humidifier tub includes a guidance structure adapted todirect air entering the humidifier tub via the air inlet to swirldownwardly and around within the humidifier tub before exiting the exitport.

Another aspect of the invention relates to a humidifier tub for ahumidifier. The humidifier tub includes an upper wall and a cylindricalor substantially conical side wall defining a water chamber, an airinlet, an air outlet, and a curved baffle provided within the waterchamber. The curved baffle extends downwardly from the upper wall andprovides a concave surface positioned between the air inlet and the airoutlet.

Yet another aspect of the invention relates to a method of humidifyingair including providing a water chamber having an air inlet and an airoutlet, directing air entering the water chamber via the air inlet in adownward direction before exiting the air outlet, and directing airentering the water chamber via the air inlet in a spiral direction downto the water surface before exiting the air outlet.

Yet another aspect of the invention relates to a humidifier including ahumidifier tub including an air inlet and an air outlet and a base plateprovided to a bottom of the humidifier tub. The base plate andhumidifier tub define a water chamber adapted to receive a volume ofwater. The humidifier tub includes a guidance structure adapted tosmoothly direct air entering the humidifier tub via the air inlet to asurface of the water before exiting via the air outlet.

Still another aspect of the invention relates to a humidifier tub for ahumidifier including a first component defining a first partial tubularair inlet flow path portion and a second component coupled to the firstcomponent and defining a second partial tubular air inlet flow pathportion. The first and second partial tubular air inlet flow pathportions cooperate to define a composite tubular air inlet flow paththat directs incoming air in a generally circular manner down and aroundwithin the tub.

Other aspects, features, and advantages of this invention will becomeapparent from the following detailed description when taken inconjunction with the accompanying drawings, which are a part of thisdisclosure and which illustrate, by way of example, principles of thisinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings facilitate an understanding of the variousembodiments of this invention. In such drawings:

FIG. 1 is a perspective view of a CPAP device including a humidifier tubaccording to an embodiment of the invention;

FIG. 2A is a perspective view of the humidifier tub shown in FIG. 1removed from the flow generator of the CPAP device;

FIG. 2B is a side view of part of the humidifier tub shown in FIG. 2A;

FIG. 2C is a perspective view of a humidifier tub according to anotherembodiment of the present invention;

FIG. 2D is a cross-sectional view through line 2D-2D of FIG. 2C;

FIG. 3 is a perspective view of the inside of the humidifier tub shownin FIG. 2A;

FIG. 4 is another perspective view of the inside of the humidifier tubshown in FIG. 2A;

FIG. 5 is a perspective view of the inside of a humidifier tub accordingto another embodiment of the invention;

FIG. 6 is another perspective view of the inside of the humidifier tubshown in FIG. 5 ;

FIG. 7A is a perspective view of a Computational Fluid Dynamic (CFD)simulation of the humidifier tub air flow shown in FIGS. 3-4 ;

FIG. 7B is a side view of a CFD simulation of the humidifier tub airflow shown in FIGS. 3-4 ;

FIG. 7C is a top view of a CFD simulation of the humidifier tub air flowshown in FIGS. 3-4 ;

FIG. 8A is a perspective view of a CFD simulation of the humidifier tubair flow shown in FIGS. 5-6 ;

FIG. 8B is a side view of a CFD simulation of the humidifier tub airflow shown in FIGS. 5-6 ;

FIG. 8C is a top view of a CPD simulation of the humidifier tub air flowshown in FIGS. 5-6 ;

FIGS. 9-10 are perspective views of a cradle and user guidance systemaccording to an embodiment of the invention;

FIGS. 11-12 are perspective views of a cradle and user guidance systemaccording to another embodiment of the invention;

FIG. 13 is a perspective view of a humidifier tub according to yetanother embodiment of the invention;

FIG. 14 is a perspective view of the inside of the humidifier tub shownin FIG. 13 ;

FIGS. 15-20 illustrate a humidifier tub according to yet anotherembodiment of the invention;

FIGS. 21-25 illustrate a humidifier tub according to still anotherembodiment of the invention; and

FIGS. 26-27 illustrate a humidifier tub and/or associatedtubing/connector according to another embodiment of the invention.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

1. Humidifier Tub

FIG. 1 illustrates a humidifier tub 50 for a humidifier 30 of a CPAPdevice 10 according to an embodiment of the present invention. Asillustrated, the CPAP device 10 includes a flow generator 20 and ahumidifier 30 provided to the flow generator 20.

The flow generator 20 includes a housing 22 and a blower (not shown)supported within the housing 22. As is known in the art, the blower isoperable to draw a supply of air into the housing 22 through one or moreintake openings and provide a pressurized flow of air at an outlet 24.In an embodiment, the flow generator 20 may be structured and controlledsuch as the flow generator described in U.S. Patent Application No.60/707,951, entitled “Low Cost CPAP Flow Generator and HumidifierAssembly,” filed Aug. 15, 2005, the contents of which are incorporatedin its entirety by reference herein.

The humidifier 30 includes the humidifier tub 50, which includes a baseplate 52 sealed to the bottom of the tub 50. Humidifier 30 includes oris associated with a heating element that may be provided to a cradle 40(FIG. 9 ). The tub 50 includes an inlet 54 adapted to be connected tothe outlet 24 of the flow generator 20, and an outlet 56 adapted to beconnected to an air delivery conduit. The air delivery conduit includesone end coupled to the outlet 56 of the tub 50 and an opposite endcoupled to a patient interface. The patient interface comfortablyengages the patient's face and provides a seal. The patient interfacemay have any suitable configuration as is known in the art, e.g.,full-face mask, nasal mask, oro-nasal mask, mouth mask, nasal prongs,etc.

The tub 50 and base plate 52 define a chamber 58 (see FIG. 3 ) that isadapted to receive a volume of water, e.g., several hundred milliliters.The inlet 54 and the outlet 56 are both communicated with the chamber58. In use, a supply of pressurized air from the flow generator 20enters the inlet 54 of the tub 50 and collects moisture through contactwith the water within the tub 50 before continuing on to the outlet 56and to the patient via the air delivery conduit.

1.1 Air Inlet Flow Tube and Air Outlet Flow Tube

As best shown in FIGS. 2A and 2B, the humidifier tub 50 has asubstantially cylindrically-shaped or curved side wall 62 and may have aslight tapering towards the upper wall or lid 60. In an embodiment, thetub 50 is molded from a plastic material, e.g., polypropylene or otherclear materials, and the tapering facilitates the ejection of the moldedtub from the manufacturing tool. The tub 50 is preferably made frompolypropylene to maintain a low cost although other suitable plasticsmay be used.

FIGS. 2C and 2D illustrate a humidifier tub 450 substantially similar tothe humidifier tub 50. As illustrated, the tub 450 includes an inlet 454and an outlet 456, and a base plate 452 is sealed to the bottom of thetub 450. In contrast to tub 50, the tub 450 includes a recess 455surrounding the inlet 454 that may facilitate connection with the flowgenerator 20.

As shown in FIGS. 2A, 2B, 3, and 4 , the inlet 54 is in the form of anair inlet flow tube and the outlet 56 is in the form of an air outletflow tube. In the illustrated embodiment, the air inlet flow tube 54enters the tub 50 at the upper edge of the sidewall 62. The air inletflow tube 54 is centrally located and extends towards the center of thetub 50. As illustrated, at least a portion of the air inlet flow tube 54is formed within the lid 60 of the tub 50, such that the upper surfaceof the air inlet flow tube 54 forms a part of the lid 60. The length ofthe air inlet flow tube 54 may vary and may extend beyond the center ofthe tub 50. Also, the air inlet flow tube 54 may be preciselyhorizontally oriented, although preferably the air inlet flow tube 54 ispositioned to have a slight downward angle across its longitudinal axis,e.g., 0°-15° or about 3°-5° slight downward angle α as shown in FIG. 2B.Of course, other angles are contemplated and the angle may be slightlyupwardly angled.

In the illustrated embodiment, the air outlet flow tube 56 is generallyvertically oriented or generally transverse to the air inlet flow tube54. As illustrated, the air outlet flow tube 56 is located in a recessedportion 64 of the tub 50 on the opposing side of the tub 50 to the airinlet flow tube 54. The recessed portion 64 is positioned slightly abovea suggested maximum water filling level (indicated by water fillingindication mark 66 in FIG. 2A). The height to which the air outlet flowtube 56 extends from the base of the tub 50 is less than the finalheight to which the bottom edge of the air inlet flow tube 54 extendsfrom the base of the tub 50. That is, the air outlet flow tube 56 has anexit port that is positioned in a plane disposed below the air inletflow tube 54. This arrangement advantageously prevents water fromflowing back into the flow generator 20 via the air inlet flow tube 54.For example, if the tub 50 is filled above the water filling indicationmark 66, the water will simply flow back out the air outlet flow tube 56rather than into the air inlet flow tube 54 and consequently into theflow generator 20 via outlet 24.

In the illustrated embodiment, the air outlet flow tube 56 issubstantially aligned with a central axis 90 of the CPAP device 10extending through the flow generator 20 and the humidifier tub 50 asshown in FIGS. 1 and 7C. Also, the air outlet 24 of the flow generator20 and the air inlet flow tube 54 of the humidifier tub 50 are offsetfrom the axis 90. This combination of the humidifier tub air outlet flowtube 56 location with the extended air inlet flow tube 54, the potentialfor water spillback into the flow generator 20 is greatly reduced shouldthe CPAP device 10 be tilted through a large angle, such as 60° orgreater, in any of the four orientations, i.e., rearwards, forwards,left or right. However, the axis 90, the air outlet flow tube 56, theair inlet flow tube 54 of the humidifier tub 50, and/or the air outlet24 of the flow generator 20 may be aligned with one another or offsetfrom one another in any suitable manner

1.2 Moisture Pickup and Airflow

To increase moisture pickup and minimize pressure loss, the interior ofthe tub 50 is designed to encourage smooth air flow that swirls down andaround the tub 50 reaching the water surface before exiting out of theair outlet flow tube 56. This flow configuration is achieved byproviding a guidance structure 70 (also referred to as a swirlingmechanism) within the tub 50.

As best shown in FIGS. 3 and 4 , the guidance structure 70 includes achamfered wall portion 72 and a curved baffle 74. As illustrated, thechamfered wall portion 72 is incorporated into the lid 60 of the tub.The chamfered wall portion 72 begins after the outlet end of the airinlet flow tube 54 and extends downwardly towards the air outlet flowtube 56. The chamfered wall portion 72 provides a chamfered face orinclined interior surface 76 positioned directly in front of incomingair from the air inlet flow tube 54. This configuration encourages theair flow to move downwardly towards the surface of the water within thetub 50.

The curved baffle 74 is provided within the interior of the tub 50 andextends downwardly from the lid 60. As illustrated, the curved baffle 74protrudes past the bottom edge of the air inlet flow tube 54. In anembodiment, the curved baffle 74 may protrude to the water fillingindication mark 66. However, the curved baffle 74 may have any suitableheight, e.g., one end of the baffle may be longer than an opposing endof the baffle. Also, the curved baffle 74 includes a generally constantthickness in the illustrated embodiment. However, the thickness of thecurved baffle 74 may vary, e.g., thickness may increase and/or decreasealong its height and/or length. The curved baffle 74 provides a concavesurface 78 positioned in front of the outlet end of air inlet flow tube54.

The curved baffle 74 acts to deflect or force incoming air to travelover a larger surface area, thereby allowing increased moisturization ofthe flow of gas. The use of a curved baffle 74 having a concave surface78 smoothly changes the direction of the air flow by gently guiding theair flow around the tub 50 in a swirling motion while limiting the lossof pressure. In contrast, sharp changes in direction cause the amount ofpressure loss to be greater.

As shown in FIGS. 3 and 4 , the curved baffle 74 includes an end portion80 that is joined to the side wall 62 of the tub 50. This arrangementprevents air from flowing around this end portion 80 of the curvedbaffle 74. Alternatively, the end portion of the curved baffle may bespaced from the side wall of the tub.

1.2.1 Curved Baffle Spaced from Side Wall

For example, FIGS. 5 and 6 illustrate a humidifier tub 250 according toanother embodiment of the invention. In this embodiment, the tub 250includes a curved baffle 274 wherein the end portion 280 of the curvedbaffle 274 is spaced from the side wall 62. That is, the end portion 280ends at a distance from the side wall 62 to provide a gap between theend portion 280 and the side wall 62. This arrangement allows somecirculating air to flow around the end portion 280 of the curved baffle274. The remaining components of the tub 250 are similar to the tub 50and indicated with similar reference numerals.

1.2.2 Air Flow Motion

The combination of the chamfered wall portion 72 and the curved baffle74, 274 (and possibly the downwardly inclined air inlet flow tube 54,254) directs the air flow in a helical motion in both a spiral anddownwards direction towards the surface of the water in the tub 50.Specifically, the concave surface 78 of the curved baffle 74 ispositioned in front of the outlet end of air inlet flow tube 54 todirect incoming air in a spiraling or swirling motion. In addition, theinclined interior surface 76 of the chamfered wall portion 72 ispositioned in front of the outlet end of air inlet flow tube 54 todirect incoming air in a downward motion towards the surface of thewater. Thus, the combination of the concave surface 78 and the inclinedinterior surface 76 direct incoming air in both a spiraling and downwardmotion, also referred to as helical motion. That is, the air has aspiraling motion with an axial component.

The chamfered wall portion 72 and the curved baffle 74 may be positionedsuch that the incoming air is directed in a spiral motion before beingdirected in a downward motion. Alternatively, the chamfered wall portion72 and the curved baffle 74 may be positioned such that the incoming airis directed in a downward motion before being directed in a spiralmotion. In addition, the spiral and downward motion may occursubstantially simultaneously.

This helical motion enhances moisture pickup. For example, the tub 50may improve moisture pickup by approximately 25% or greater compared toprior art tubs.

1.2.3 Computational Fluid Dynamic (CFD) Analysis

Computational fluid dynamic (CFD) analysis of 3D models of the twoabove-described tubs 50 and 250 having different baffle designs wereperformed with a volume flow of about 100 L/min applied at the air inletflow tube 54 and a pressure of about 12 cm H₂O at the air outlet flowtube 56. In the illustrated embodiment, the two tubs 50 and 250 havesubstantially similar exterior surfaces. In contrast, the tub 50includes an end portion 80 of the baffle 74 that is joined to the sidewall 62, while the tub 250 includes an end portion 280 of the baffle 274that is spaced from the side wall 62 to provide a gap.

The pressure drop between air inlet flow tube 54 and air outlet flowtube 56 in cmH₂O is shown in the table below. As illustrated, thepressure drop for the tub 250 is slightly smaller than the pressure dropfor the tub 50.

Pressure Drop Inlet- Outlet Tub Option (cm H₂O) 1-Baffle 74 joined 0.77to side wall 62 2-Gap 0.69 between baffle 274 and side wall 62

Air flow lines of the tub 50 are shown in FIGS. 7A-7C, and air flowlines of the tub 250 are shown in FIGS. 8A-8C. As illustrated, each ofthe tubs 50, 250 presents a characteristic of swirling flow as the airmeets the respective curved baffle 74, 274 and downward flow as the airmeets the chamfered wall portion 72 as described above. As best shown inFIGS. 8A and 8C, the tub 250 allows some of the air flow, indicated asLi, to take a shortcut path behind the baffle 274 to the air outlet flowtube 56 via the gap between the baffle 274 and the side wall 62. Thisarrangement results in a slightly smaller pressure drop for the tub 250due to less flow restriction.

Also, the velocity of the air flow is similar for both tubs 50, 250 withthe velocity of the air flow within the air inlet and air outlet flowtubes 54, 56 being substantially higher than the velocity within the tubinterior. Due to different baffle designs, the localized velocity in theair inlet flow tube 54 is slightly higher for the tub 50.

Further benefits of providing better mixing of air and moisture pickupinclude a reduced water temperature for a given delivered air moisturecontent, which results in less electrical energy usage by the heaterelement and lower casing temperature. The reduced pressure loss meansthat the motor power of the flow generator 20 does not need to increaseto compensate for this pressure loss. This saves motor power by loweringmotor speed, which also results in reduced noise levels.

The baffle 74, 274 also prevents short-circuiting of the air flow fromthe air inlet flow tube 54 directly to the air outlet flow tube 56. Thelength of the baffle 74, 274 may vary, but its configuration andpositioning provide a barrier between the air inlet and air outlet flowtubes 54, 56 and encourage swirling of the air entering the tub 50, 250.

In the illustrated embodiments, the baffle 74, 274 extends generallyvertically into the tub interior. However, the baffle 74, 274 may beangled with respect to vertical such that it tilts away from the aircoming towards it. This arrangement may provide a gentler change in airmovement within the tub 50, 250 and consequently provide a lowerpressure loss.

1.3 User Guidance System

The humidifier tub 50, 250, 450 may be designed to facilitate attachmentto a cradle upon which it sits. The cradle is structured to support thehumidifier 30 in an operative position with respect to the flowgenerator 20.

For example, FIGS. 9 and 10 illustrate a cradle 88 including a supportsurface 90 for supporting the flow generator 20 thereon and a supportsurface 92 for supporting the humidifier thereon. The support surface 92may include a heating element for heating a heat conducting base of thehumidifier. As illustrated, the tub 450 includes flattened sides 482that slightly taper or converge towards the flow generator side of thetub 450 (also see flattened sides 282 of tub 250 in FIG. 5 ). Theflattened sides 482 are configured to allow correct placement andalignment of the tub 450 on the cradle 88. The flattened sides 482 alsoidentify the correct orientation of the tub 450. Specifically, thecradle 88 includes opposing side walls 94 that provide guiding surfaces96 that engage the flattened sides 482 of the tub 450 to guide the tub450 onto the cradle 88. Also, the side walls 94 provide slots 98 thatguide the base of the humidifier onto the cradle 88. FIG. 10 illustratesthe tub 450 aligned and positioned on the cradle 88. The flattened sideshelp to automatically align during docking. The flattened sides alsoprovide easy and intuitive gripping surfaces for the patient.

In an alternative embodiment or in addition to flattened sides, the tub50, 250, 450 may include a vertical vane adapted to engage acorrespondingly shaped slot or recess provided on the cradle 88. Forexample, FIGS. 11 and 12 illustrate a humidifier tub 550 including avertical vane 502 located on the external surface on the flow generatorside of the tub 550. The vertical vane 502 may be positionedperpendicularly to the side wall 562. The vertical vane 502 may be anysuitable shape and is designed to fit or dock into a correspondinglyshaped slot or recess 504 provided within the cradle 88 to ensurecorrect positioning of the tub 550 on the cradle 88. The opening of thecorresponding slot or recess 504 on the cradle 88 may be designed to bewider at its periphery and become progressively narrow towards the finaldocking position. This allows more movement when initially aligning thetub vane 502 with the docking slot or recess 504 while ensuring the tub550 is ultimately correctly docked. FIG. 12 illustrates the tub 550aligned and positioned on the cradle 88 via the vane 502/slot 504arrangement. However, it is noted that the reverse arrangement wouldalso provide the same alignment benefits. Thus, the docking slot orrecess 504 may be located on the humidifier tub 550 and the vane 502 maybe located on the cradle 88 (not shown).

1.4 Base Plate

As noted above, a base plate 52, 452 is sealed to the bottom of the tub50, 250, 450, 550 to define the chamber 58 that receives a volume ofwater (best shown in FIG. 2D). The base plate 52, 452 may be removablymounted to the tub 50, 250, 450, 550 to allow the tub 50, 250, 450, 550to be cleaned. In an embodiment, the bottom of the tub 50, 250, 450, 550and the base plate 52, 452 may have a “jam-jar” screw-on design.

Also, the base of the tub 50, 250, 450, 550 may include a siliconegasket or other suitable material for sealing to the base plate 52, 452.Further, the base plate 52, 452 may be in the form of a heat conductingbase plate. Specifically, the base plate 52, 452 may be formed of a heatconducting material, e.g., stamped anodized thin gauge aluminum which isknown to provide excellent heat conducting properties. The aluminum baseplate 52, 452 may have a stamped rolled edge to clamp the siliconegasket used for sealing.

1.5 Humidifier Tub (S9) with S-Shaped Baffle

FIGS. 13 and 14 illustrate a humidifier tub 350 according to anotherembodiment of the invention. As illustrated, the humidifier tub 350includes an air inlet 354 and an air outlet 356 provided through anupper wall of the tub 350. The air outlet 356 is located near a centralaxis of the tub 350. The air flow initially enters the tub 350 in adownwards direction towards the surface of the water.

The tub 350 also includes an S-shaped baffle 374 that curves around theoutlet end of the air inlet 354 and then around the inlet end of the airoutlet 356 as shown in FIG. 14 . This arrangement provides a barrierbetween the air inlet 354 and air outlet 356 to prevent incoming airfrom short-circuiting directly to the air outlet 356. Further, thelocation of the outlet end of the air inlet 354 together with the baffle374 and curve shaped side walls 362 encourage incoming air to swirlaround and down into the tub 350 thereby providing excellent moisturepickup.

1.6 Alternative Embodiments of Humidifier Tub

FIGS. 15-20 illustrate a humidifier tub 650 according to yet anotherembodiment of the invention. As illustrated, the humidifier tub 650 isconstructed of two separate components that are coupled to one another.Specifically, the humidifier tub 650 includes an upper portion 651 and alower portion 653 coupled to the upper portion 651. As best shown inFIGS. 17-18 , the upper portion 651 includes an air inlet flow tube 655and a roof 657 and side sections 659 of an air flow path 660 thatdirects incoming air down and around within the tub 650. As best shownin FIGS. 19-20 , the lower portion 653 includes the floor or bottomsection 661 of the air flow path 660 and provides a barrier 669 betweenthe air flow path 660 and the bottom of the tub 650. An inlet opening663 is provided that allows air to enter the chamber defined by the sidewall 665 of the lower portion 653.

When the upper and lower portions 651, 653 of the tub 650 are coupled toone another (see FIGS. 15 and 16 ), they cooperate to define the airflow path 660 that directs the air flow around and down towards thebottom of the tub 650 to the water surface. As illustrated, the air flowpath has a generally circular configuration. The shape and structure ofthe air flow path 660 provides the guidance for the air flow. In anembodiment, the roof 657 and/or floor 661 may have a slope to promotespiral or helical motion.

The air outlet flow tube 667 is centrally located and formed in thelower portion 653 of the tub 650. This arrangement allows air to exitout the top of the tub 650. In this embodiment, the air outlet flow tube667 is not positioned below the air inlet flow tube 655. However, thetub 650 does provide spill-back protection due to the barrier 669between the upper and lower portions 651, 653 of the tub 650. Thisarrangement may be similar to the spill-back design used on ResMed's H3iHumidifier disclosed in WO 2004/112873, incorporated herein by referencein its entirety.

FIGS. 21-25 illustrate a humidifier tub 750 according to still anotherembodiment of the invention. As illustrated, the humidifier tub 750 isconstructed of two separate components that are coupled to one another.Specifically, the humidifier tub 750 includes a tub portion 751 and abarrier portion 753 coupled to the tub portion 751. As best shown inFIG. 23 , the tub portion 751 includes an air inlet flow tube 755 and aroof 757 and side sections 759 of an air flow path 760 that directsincoming air down and around within the tub 750. As best shown in FIGS.24-25 , the barrier portion 753 includes the floor or bottom section 761of the air flow path 760 and provides a barrier 769 between the air flowpath 760 and the bottom of the tub 750. An inlet opening 763 is providedthat allows air to enter the chamber defined by the side wall 765 of thetub portion 751.

When the barrier portion 753 is coupled to the tub portion 751 (see FIG.22 ), they cooperate to define the air flow path 760 that directs theair flow around and down towards the bottom of the tub 750 to the watersurface. In the illustrated embodiment, the tub portion 751 includeslocking members 771 that engage an aperture 773 provided in the barrierportion 753 with a snap-fit. However, the barrier portion 753 may beattached to the tub portion 751 in other suitable manners. Asillustrated, the air flow path has a generally circular configuration.The shape and structure of the air flow path 760 provides the guidancefor the air flow. In an embodiment, the roof 757 and/or floor 761 mayhave a slope to promote spiral or helical motion.

The air outlet flow tube 767 of the tub 750 is centrally located andformed in the tub portion 751 of the tub 750. This arrangement allowsair to exit out the top of the tub 750.

1.6.1 Alternative Port Structure

As shown in FIGS. 2A and 2C, the humidifier tub has an outlet in theform of an outlet tube 54, 254 that extends upwards from an inset ledge.With this construction, an air delivery conduit (not shown) includes afitting into which the conduit is inserted to establish fluidcommunication between the tub and the air delivery tube.

In an alternative as shown in FIG. 26 , a humidifier tub 800 may includea main body 804 with an inlet conduit portion 805 like that shown inearlier embodiments and an outlet 810 which differs from the outletsshown in earlier embodiments. Outlet 810 includes a female fitting 815,preferably in the form of a conical section. Fitting 815 is compatiblewith a standard fitting 820 that has a lower portion 825 with asimilarly shaped but smaller diameter conical fitting. Standard fitting820 is inserted into or within the outlet fitting 815. An air deliveryconduit 830 may be coupled to an upper portion 835 of the standardfitting 820. In use, the standard fitting 820 and the air deliveryconduit 830 are preferably attached to and detached from the tub outlet810 as one unit, which is easier for the patient or clinician since themating of the two conical surfaces is generally self locating and takesless effort than standard connections where the user may struggle toattach the rubber fitting of air delivery conduit to the humidifieroutlet, which connection may involve strong frictional forces. Thisarrangement also facilitates the use of an antibacterial filter 840(FIG. 27 ) that has one end coupled to the standard fitting and anotherend coupled to the air delivery tube.

While the invention has been described in connection with what arepresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the invention. Also, the various embodiments described abovemay be implemented in conjunction with other embodiments, e.g., aspectsof one embodiment may be combined with aspects of another embodiment torealize yet other embodiments. In addition, while the invention hasparticular application to patients who suffer from OSA, it is to beappreciated that patients who suffer from other illnesses (e.g.,congestive heart failure, diabetes, morbid obesity, stroke, barriatricsurgery, etc.) can derive benefit from the above teachings. Moreover,the above teachings have applicability with patients and non-patientsalike in non-medical applications.

What is claimed is:
 1. A humidifier tub with a chamber configured tocontain a body of water and humidify a pressurized flow of respiratorygas, the humidifier tub comprising: a first side and a second sideopposing the first side, the first side having an air inlet openingconfigured to receive the pressurized flow of respiratory gas; an airoutlet opening configured to discharge the pressurized flow ofrespiratory gas with added humidity; an inlet passage extending from theair inlet opening toward the second side so that the pressurized flow ofrespiratory gas travels through the inlet passage in a first direction;a guidance structure located between the first and second sides andpositioned so that a traveling direction of the pressurized flow ofrespiratory gas changes from the first direction to a second directionupon the pressurized flow of respiratory gas engaging the guidancestructure; a lid forming a top side of the chamber, the guidancestructure extending downward from the lid; and a heat conducting baseplate located on a bottom side of the chamber, wherein the firstdirection is a lateral direction and the second direction is a downwarddirection.
 2. The humidifier tub of claim 1, wherein the first andsecond directions are orthogonal to each other.
 3. The humidifier tub ofclaim 1, further comprising an outlet passage extending into the chamberfrom the air outlet opening.
 4. The humidifier tub of claim 1, whereinthe guidance structure comprises a curved wall.
 5. The humidifier tub ofclaim 1, wherein the guidance structure extends from an upper surface ofthe lid.
 6. The humidifier tub of claim 1, wherein the inlet passage isintegrally formed with an upper surface of the lid so that an uppersurface of the inlet passage forms part of the lid.
 7. The humidifiertub of claim 1, wherein the air outlet opening is not below the airinlet opening.
 8. The humidifier tub of claim 1, wherein a bottom of theguidance structure is below the air outlet.
 9. The humidifier tub ofclaim 1, wherein the guidance structure is located at an end of theinlet passage.
 10. The humidifier tub of claim 1, further comprising anoutlet passage extending into the chamber from the air outlet opening,wherein the first and second directions are orthogonal to each other,wherein the guidance structure comprises a curved wall, wherein theguidance structure extends from an upper surface of the lid, and whereinthe inlet passage is integrally formed with the upper surface of the lidso that an upper surface of the inlet passage forms part of the lid, andwherein the air outlet opening is not below the air inlet opening.
 11. Arespiratory device comprising: a flow generator configured to pressurizea flow of respiratory gas; the humidifier tub of claim 1; and ahumidifier base configured to receive the humidifier tub.
 12. Therespiratory device of claim 11, further comprising a housing configuredto support both the flow generator and the humidifier base.
 13. Therespiratory device of claim 12, wherein the humidifier base comprises aheater plate configured to engage the base plate of the humidifier tubupon the humidifier tub being received by the humidifier base.
 14. Ahumidifier tub with a chamber configured to contain a body of water andhumidify a pressurized flow of respiratory gas, the humidifier tubcomprising: a first side and a second side opposite the first side, thefirst side having an air inlet opening configured to receive thepressurized flow of respiratory gas; an air outlet opening configured todischarge the pressurized flow of respiratory gas with added humidity; aguidance structure configured to direct the pressurized flow ofrespiratory gas through the chamber, the guidance structure comprising:a first portion configured to direct the respiratory gas in a firstdirection from the air inlet opening toward the second side of thehumidifier tub; and a second portion located between the first andsecond sides of the humidifier tub and positioned so that a travelingdirection of the pressurized flow of respiratory gas changes from thefirst direction to a second direction upon the pressurized flow ofrespiratory gas engaging the second portion of the guidance structure; alid forming a top side of the chamber, the second portion of theguidance structure extending downward from the lid; and a heatconducting base plate located on a bottom side of the chamber, whereinthe first direction is a generally horizontal direction and the seconddirection is a downward direction.
 15. The humidifier tub of claim 14,wherein the first and second directions are orthogonal to each other.16. The humidifier tub of claim 15, wherein the second portion of theguidance structure extends downward from an upper surface of the lid.17. The humidifier tub of claim 15, wherein the first portion of theguidance structure is in the form of a laterally extending air flowpassage that extends from the air inlet opening into the chamber. 18.The humidifier tub of claim 15, wherein the first direction is agenerally horizontal direction and the second direction is a downwarddirection.
 19. The humidifier tub of claim 15, further comprising anoutlet passage extending into the chamber from the air outlet opening.20. The humidifier tub of claim 15, wherein the second portion of theguidance structure comprises a curved wall.
 21. The humidifier tub ofclaim 15, wherein the guidance structure extends from an upper surfaceof the lid.
 22. The humidifier tub of claim 15, wherein the firstportion of the guidance structure is integrally formed with an uppersurface of the lid so that an upper surface of the first portion of theguidance structure forms part of the lid.
 23. The humidifier tub ofclaim 15, wherein the air outlet opening is not below the air inletopening.
 24. The humidifier tub of claim 15, further comprising anoutlet passage extending into the chamber from the air outlet opening,wherein the first and second directions are orthogonal to each other,wherein the second portion of the guidance structure extends downwardfrom an upper surface of the lid, wherein the first portion of theguidance structure is in the form of a laterally extending air flowpassage that extends from the air inlet opening into the chamber,wherein the second portion of the guidance structure comprises a curvedwall, wherein the guidance structure extends from an upper surface ofthe lid, wherein the first portion of the guidance structure isintegrally formed with an upper surface of the lid so that an uppersurface of the first portion of the guidance structure forms part of thelid, and wherein the air outlet opening is not below the air inletopening.
 25. A respiratory device comprising: a flow generatorconfigured to pressurize a flow of respiratory gas; the humidifier tubof claim 15; and a humidifier base configured to receive the humidifiertub.
 26. The respiratory device of claim 25, further comprising ahousing configured to support both the flow generator and the humidifierbase.
 27. The respiratory device of claim 26, wherein the humidifierbase comprises a heater plate configured to engage the base plate of thehumidifier tub upon the humidifier tub being received by the humidifierbase.